Broadcast antenna



R. w. MASTERS BROADCAST ANTENNA Filed May 29, 19 5 June 20, 1950 INVENTOR gaze/211511 51615 ATTORNEY Patented June 20, 1950 x a v BROADCAST ANTENNA- Robert Masters, Erlton N J assignor to Radio Corporationof America,,a corporation of Delae w if i n puean nMayze, 194 Serial No. 672,950

; L10 Claims. (o1. zen-es) The presentinvention relatesto'antennas and more particularly to broad band antennas suit- ,able for televisionbroadcast operation,

An objectof the present invention to provide an antenna structure'which will permit the ad jjustment of the impedance characteristic thereof without in any way altering th'e' shape of the radiation pattern. o a Another object of thejpre'ser'itinvention is to j increase the band coverage of a television broadc'astiantenna'. v v l Still another object of the present invention is to provide anantenna system'which isless frequency selective in the neighborhood o fflagiven frequency than heretofore kno'wn antennas. I Still another object offthe' present"'invention is the, provision of a' simple A broadcast antenna .system which may easily be adjusted for optimum operating characteristics. T' l ,{The foregoing object and others which may l-appear fronithe' following detailed description jareattained by utilizinga dipole antenna having conductive screen radiator elements ,ashdescribed in myfc'opending U. S. patent applications, Serial lion 5'l4=,898,'v filed January 27,1945, Serial No. 574,899,,fi1ed January ,27, 1945 and Serial No. 580,120; filed February 28; 1945, respectively ,Patent Numbers 2,480,153; to 2,480,154; and 2,480,155, granted Aug' stao; 19 19.. f

. vThe screen radiatrelements; of the an tennas disclosed in o the above-mentioned applications are, in the presentinventiom modified so as to ,contain within each of therscr 'een radiator elements'a section, of afcoaxialline constituting a dissipationless reactance netwo rk which may be connected either in series with the radiator element or in shunt from the radiator element to the ground. Thus, the operating parameters of the antenna may readilybeadj usted.v

Thepresent invention will be morefully understood by reference to the following detailed description which is accompanied by a drawing in which: v 1

' Figure 1 illustrateslin elevation and partly in section an embodiment of the present invention, while i Figure 2 illustratesa modifiedform of them- .ventionu v ,1 x Referring now to Figure 1, there is shown an antenna including-at least a pair of plane screen radiator elements l and -l each including a sub-v stantially rectilinear edge 3 and 3' respectively. The rectilinear edges 3 and 3" may each beioi the order of one-half wavelength long at the operating frequency. The antenna is not limited to the particular form of constructionhere shown since radiator, elements each comprise a plurality of horizontally disposed rod or tubular members spaced from each other by a small fractionoi a wavelength. The horizontally disposed members thus effectively act as a single radiator as though it were a conductive sheet. The radiators I and I, are preferably supported on a conductive mast 5 by means of brackets I at the upper and lower ends of the inner edges 3 and 3. Mast ineed not necessarily be conductive. Under some oil cumstances it may be desirable to use a wooden or non-conductive mast. Also, if desired, the mast may be omitted, the sheet radiatorelements themselves being self supporting. Snorting clips 11 may be provided to electrically connect the rectilinear edges 3 and 3' at selected points to the conductive mast 5. The screen radiator elements l and I! are preferably energized by'means of coaxial transmission lines, only one of which is actually shown in the drawing. This coaxialline is associated with radiator element I' andfis identified by reference character TL. The outer conductor 15 of transmission line TL may be electrically connected to the conductive mast 5'. The inner conductor It may be coupled to radiator element I through the intermediary of a series reactance network I 8. ,'In arrangements j-wherein no mast or a non-conductive mast is used, the energization of the radiating elements also may be accomplished as explained in m'y prior application Serial No. 580,120, filed February 28, 1945. The series reactance network lS'includes a hollow tubular member 19 lying along rectilinear edge 3 of radiator I. It may bean integral part of the conductive structure or may be a separate tube welded or otherwise secured along edge '3. Within the tubular member 19 and electrically directly connected to inner conductor I6 of the transmission line TL is an inner conductor 20. In order that the reactance effect of network I 8 may be varied conductor 2;) is arranged to have its length conveniently variable. This may be done by providing a close fitting conductive sleeve 2| arranged to slide over the conductor, 20, and acts as an extension thereof. Suitable access holes may be provided at the lower end of tubular member l9 whereby an actu ating rod may be inserted to engage tubular sleeve 2|, whereby the effective electrical length. of the conductor constituted by members 20 and 2| may be adjusted. It is desirable to support members :20 andZl in a coaxial relationship within tubu-.- lar member l9 by means of insulating spacers such as those indicated at 22. While Ihave not so shown the structure, it may be desirable that the transmission'line TL and the series impedance matching section l8 be weatherproofed to prevent the entry of rain and moisture into thespace between the inner and outer conductors thereof. \1$ S. d 0 -,0P. a .th e t men??? sion lines will then be energized in a push-pull relationship from a single transmitter.

The present improvement may also be applied to a turnstile type of radiator wherein four screen radiator elements are utilized, spaced at mutual angles of 90 around a conductive mast and fed in a mutual phase quadrature relationship. This arrangement and the manner of energizing the transmission lines is described in greater detail in one or more of the previously filed applications mentioned above, to which reference may be made for complete details.

The modified form of the invention shown in Figure 2 utilizes the same general arrangement of the screen radiator elements I and I and the conductive mast 5 as described with reference to Figure 1. Likewise the radiators are similarly mounted and the mounting means are given the same reference numerals as in the case of Figure 1. of Figure 2 the reactance network 28 is connected in' shunt to the input of the radiator; that is, across the points to which the conductors of the transmission line TL are connected. Thus, the inner conductor l6 of the transmission line EL is directly connected to the rectilinear edge 3' of the radiator member I while the inner conductorof the reactance network 28 is connected to mast'5'. In a dipole arrangement using aninsulating mast, conductor 30 isconnected to the opposite polarity input' terminal. Theexterior conductors should be as short as possible, or at least symmetrical. The inner conductor 30 of the reactance network 28 is connected to the interior of tubular member [9 by a shorting plug 3|, sliding within the tubular member 19. Its position may be varied up and down the length of tube I9 to vary the effective electricallength of the shunt transmission linesection, constitutmg the shunt reactance 28. I

It-wi1l be apparent from an'inspecti'on of Figuies. 1 and 2 that the adjustable reactance-networks effectively form an integral part of the radiating screen structures since the tubular members l9 may actually constitute a vertical stiffening rib for the edge ofv the radiator near thesupporting pole 5. The length ofthe radiators are such that nearly a half wave of line maybe used if needed.

While I have illustrated a particular embodiment of the present invention, it should be clearly understood that it is not limited thereto since many modifications may be made in the several elements employed and in their arrangement, and it is therefore contemplated by the appended claimsto cover any such modifications as fall Within the spirit and'scope of theinvention.

What is'claimed is:

1. An antenna system including a conductive supporting member and a pair of radiating members, said radiating. members being constituted by a pair of hollow tubular conductors arranged adjacent and parallel'to said supporting memher, said conductors being connected together at the ends thereof through thev intermediary of said conductive supporting member and a plurality of further conductors arranged ina single plane and normal to said tubular conductors, said further conductors having: lengths from" a-at thecentrafpart" of However, in the modification 4 said tubular conductors to a maximum near the ends of said tubular conductors, and other conductors connecting the ends of said further conductors remote from said tubular conductors to completely close the structure of said radiating members, an inner conductor arranged within one-of said tubular conductors to form a section of concentric transmission line, means to vary the. efiective electrical length of said section of concentric line,.a coaxial transmission line having center and sheath conductors, said sheath conductor being-- connected to said conductive supporting member, and means to couple said coaxial transmission line to one of said radiating members, said means including interconnections between said center and said sheath conductors and said inner andisaid tubular conductors.

2. An antenna" system including a conductive supporting'memb'er and a pair'ofradiating members; said radiating members being constituted by a pair of hollow tubular conductors arranged adjac'entand parallel to said supporting member, said conductors being connected together at the ends thereof throughthe intermediary of said conductive supporting member and a plurality of further conductors arranged in a singleplane and norr'na'lto said tubular conductors,.said fur.- ther conductors" having 'lengths' varying from a minimum atthe central'pa'rt of saidtubular conductors to" a maximum near' the ends" of said tubular conductors, V and other" conductors connecting the" endsof' said" further conductors remote" from said tubular conductors to completely close the structure of said radiating, members. an'inner" conductor arranged within one of said tubular conductors; meansito. vary the effective electrical length of saidinner' conductor; a" transmission line having center and sheath conduc tors, said." sheath" conductor being. connected to said: conductive" supporting member; and means toconnec't said. centerconductor to saidiinner conductor.

3. An antenna system including a' conductive supporting member and a'pair of radiatlng'mem bers; said radiating members being" constituted by a-pairo'f hollow f tiibularconductors arranged adjacent and parallel to said supportingmem=- her, said" conductors being" connected together at' 'th'e-ends thereof through the intermediary of saidbo'n'cluctiixesupportingmember a'nda plurality" of further conductors arranged in a' single plane and normal to said tubular conductors, said further crinniictors having lengths varying from a minimum at"'tlie"central part of said tubular conductorsto a maximum near the ends of'sa'idtubularconductors; and other conductors connecting the ends of said further" con ductors remote from said tubular conductors to completely close the structure"of'said-r'adiatingmember's; an inner conductor-arrangedwithin one of said tubular conductors, means to-Vary th'eeifec'tive electrical length of said inner conductor, means to connect said inner conductor to said sup'por'tingmember, a transmission line having center and sheath conductors said" sheath conductor' being connected tosaid conductive supporting member, and means toconnect said c'enterconductortosaid tubular conductor.

l. An antenna system" including a conductive supportingmemberand'a-radiating member comprising a' hbllow'tubular conductor arranged" ad jacent' and parallelto said supporting member, said'conductorbe'ing connected at the end'thereof to said conductive supporting member, a plural ity of further conductorsarranged in a sin'gle plane and normal to said tubular conductor, and another conductor connecting the ends of said further conductors remote from said tubular conductor to completely close the structure of said radiating member, an inner conductor arranged within said tubular conductor, means to vary the effective electrical length of said inner conductor, said inner conductor being connected to said conductive supporting member, and means to couple a source of high frequency energy between said supporting members and said radiator.

5. An antenna system including a conductive supporting member and a radiating member comprising a hollow tubular conductor arranged adjacent and parallel to said supporting member, said conductor being connected at the end thereof to said conductive supporting member, a plurality of further conductors arranged in a single plane and normal to said tubular conductor, and another conductor connecting the ends of said further conductors remote from said tubular conductor to completely close the structure of said radiating member, an inner conductor arranged within said tubular conductor, means to vary the effective electrical length of said inner conductor, and means to couple a source of high frequency energy between said supporting member and said inner conductor.

6. An antenna system including a conductive supporting member and a radiating member comprising a hollow tubular conductor arranged adjacent and parallel to said supporting member, said conductor being connected at the end thereof to said conductive supporting member, a plurality of further conductors arranged in a single plane and normal to said tubular conductor, said further conductors having lengths varying from a minimum at the central part of said tubular conductor to a maximum near the ends of said tubular conductor, and another conductor connecting the ends of said further conductors remote from said tubular conductor to completely close the structure of said radiating member, an inner conductor arranged within one of said tubular conductors, means comprising a close fitting conductive sleeve carried by and extending beyond the end of said inner conductor to vary the effective electrical length thereof, a transmission line having center and sheath conductors, said sheath conductor being connected to said conductive supporting member, and means to connect said center conductor to said inner conductor.

'7. An antenna system including a conductive supporting member and a radiating member comprising a hollow tubular conductor arranged adjacent and parallel to said supporting member, said conductor being connected at the end thereof to said conductive supporting member, a plurality of further conductors arranged in a single plane and normal to said tubular conductor, said further conductors having lengths varying from a minimum at the central part of said tubular conductor to a maximum near the ends of said tubular conductor, and another conductor connecting the ends of said further conductors remote from said tubular conductor to completely close the structure of said radiating member, an inner conductor arranged within one of said tubular conductors, means comprising an adjustable conductive member shorting said tubular conductor to said inner conductor to vary the effective electrical length thereof, said inner con- 6 ductor being connected to said supporting member, a transmission line having center and sheath conductors, said sheath conductor being connected to said conductive supporting member, and means to connect said center conductor to said radiator.

8. An antenna system including a conductive supporting member and a pair of radiating members, said radiating members comprising a pair of hollow tubular conductors arranged adjacent and parallel to said supporting member and being connected at the ends thereof to said conductive supporting member and a plurality of further conductors arranged in a single plane and normal to said tubular conductor, an inner conductor arranged within said tubular conductor, means to vary the elfective length of said inner conductor, a transmission line having center and sheath conductors, said sheath conductor being connected to said conductive supporting member, and means to connect said centei conductor to said inner conductor.

9. An antenna system including a conductive supporting member and a pair of radiating memhere, said radiating members comprising a, pair of hollow tubular conductors arranged adjacent and paraliel to said supporting member and being connected at the ends thereof to said conductive supporting member and a plurality of further conductors arranged in a single plane and normal to said tubular conductor, an inner conductor arranged within said tubular conductor, means comprising a close fitting sleeve carried by and extending beyond the end of said inner conductor to vary the effective electrical length thereof, a transmission line having center and sheath conductors, said sheath conductor being connected to said conductive supporting member, and means to connect said center conductor to said inner conductor.

10. An antenna system including a conductive supporting member and a pair of radiating memhere, said radiating members comprising a pair of hollow tubular conductors arranged adjacent and parallel to said supporting member and being connected at the ends thereof to said conductive supporting member and a plurality of further conductors arranged in a single plane and normal to said tubular conductor, an inner conductor arranged within said tubular conductor, means comprising an adjustable conductive member shorting said tubular conductor to said inner conductor to vary the effective electrical length thereof being connected to said supporting member, a transmission line having center and sheath conductors, said sheath conductor being connected to said conductive supporting member, and means to connect said center conductor to said radiator.

ROBERT W. MASTERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,2?51330 Epstein Mar. 3, 1942 2,234,434 Lindenblad May 26, 1942 2,433,183 Wolf Dec. 23, 1947 2,480,155 Masters Aug. 30, 1949 2,483,240 Shanklin Sept. 27, 194:9 

